A screw compressor includes: a pair of male and female screw rotors each including a screw part and shaft portions formed on both ends of the screw part; a housing having a screw chamber for accommodating the screw part and a bearing chamber for accommodating the shaft portions; and a bearing, disposed in the bearing chamber, for rotatably supporting the shaft portions.
For the oil-flooded screw compressor, lubricating oil is supplied to the bearing that rotatably supports the shaft portions and to screw lobe surfaces which engage with one another to form a compressor chamber.
In a typical oil-flooded screw compressor, a part of lubricating oil supplied to the bearing is fed to the screw chamber through a flow passage formed through a housing wall, and is discharged from the screw chamber with a compressed discharge gas. The discharge gas including the lubricating oil is separated from the lubricating oil, and the separated lubricating oil is reused as lubricating oil.
Patent Document 1 discloses an oil-flooded screw compressor system aimed at preventing erosion of a bearing by a gas to be compressed that gets mixed with lubricating oil and reaches the bearing, in a case where the gas to be compressed contains an erosive component. In this oil-flooded screw compressor system, lubricating oil is supplied to the screw chamber and to the bearing chamber through different supply systems, and a seal structure is provided, which prevents entry of a gas to be compressed containing an erosive component to the bearing chamber. Accordingly, erosion of the bearing by the erosive component is prevented.